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A novel and cost-effective method for the fabrication of highly conductive Al/Ag core-shell structured microspheres was proposed and investigated. The oxidative co-deposition of catechol and polyamine was firstly performed to modify the surface of the aluminum microsphere. Then, a two-step electroless plating was conducted to fabricate the Al/Ag microspheres. During the first step of the electroless plating process, the surface of the aluminum microsphere was deposited with silver nanoparticle seeds using n-octylamine and ethylene glycol. Then, during the second step of the electroless plating process, silver particles grew evenly to form a compact silver shell on the surface of aluminum via a silver mirror reaction. According to the scanning electron microscope and energy dispersive X-ray results, a compact and continuous silver layer was successfully generated on the surface of the aluminum. The valence of the sliver on the surface of the aluminum was confirmed to be zero, based on the X-ray photoelectron spectrometer and X-ray diffractometer analyses. As a result, the as-prepared Al/Ag microspheres exhibited a high conductivity of 10,000 S/cm. The Al/Ag/MVQ composite demonstrated low electrical resistivity of 0.0039 Ω·cm and great electromagnetic interference shielding effectiveness at more than 70 dB against the X-band, and this result suggests that the as-prepared composite is a promising conductive and electromagnetic shielding material. [ABSTRACT FROM AUTHOR]

In this work, a green and efficient method for the surface modification of aramid fibers is proposed, aiming to enhance their adhesion property with rubber matrix. The surface of the aramid fibers was pre-deposited with a polyphenol-metal complex coating via rapid (1 min) complexation between FeIII ions and tannic acid (TA), followed by silane grafting. The influences of reactant concentration and reaction temperature on the grafting efficiency of bis-(γ-triethoxysilylpropyl)-tetrasulfide (Si69) were also characterized. The adhesion force of the modified aramid fibers/rubber composites showed a maximum improvement of 73.6% compared to that of untreated aramid fibers/rubber composites. This approach showed great potential in rubber industry due to its low-cost and high-efficiency. [ABSTRACT FROM AUTHOR]

In this study, the surface of ultra-high-molecular-weight-polyethylene (UHMWPE) fibers was modified by ozone pretreatment, followed by ultraviolet (UV) grafting, to enhance the interfacial properties of UHMWPE fibers/rubber composites. The fibers were first pretreated by ozone to introduce oxygen-functional groups. The graft polymerization of glycidyl methacrylate (GMA) onto the ozone-treated fibers was implemented by UV irradiation. The effects of time and GMA concentration on the grafting efficiency were investigated. The modified fibers were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). The XPS and FTIR results revealed that GMA was successfully grafted onto the fibers with epoxy groups. SEM images confirmed that a continuous layer of poly-(GMA) (PGMA) was grafted onto the fibers. The interfacial adhesion force of UHMWPE fibers with rubber matrix was characterized by H pullout testing, which showed that the maximum force the fibers/rubber composites increased by 79% over that of the untreated fibers. [ABSTRACT FROM PUBLISHER]

Abstract: A facile method was developed to prepare silica–silver core–shell composite microspheres with continuous, compact, and conductive silver layers. The procedure involves dopamine oxidative self-polymerization and electroless plating. The poly(dopamine) layer was used as the chemi-sorption sites for silver ions and promoted the silver deposition. The electroless plating procedure involves a combination of surface activation, seeding growth, and deposition. The chemical composition and the crystal structure of the silica–silver core–shell composite microspheres were studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. In addition, the surface morphology and chemical composition of each composite microsphere were confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The results demonstrated that the silver layer on the silica surface was continuous and compacted. [Copyright &y& Elsevier]

A plasma-assisted surface modification method was introduced to enhance the interfacial adhesion of rubber composites reinforced with ultra-high molecular weight polyethylene (UHMWPE) fibers. First various reactive monomers were grafted onto the fiber surface via a plasma-assisted radical polymerization reaction. Subsequently, the grafted fibers underwent RFL (resorcinol-formaldehyde-latex) dipping process to bolster their interfacial adhesion with rubber. Compared with the original UHMWPE fibers, the modified fiber-reinforced rubber composites showed an increase in H pull-out force by 105.3 %–165.7 N and peel strength by 145.2 % to 10.3 N/mm, reaching the level of general-purpose fabric-core conveyor belt (≥4.5 N/mm). After the modification, the dynamic fatigue life and aging stability of the fiber-reinforced rubber composites were significantly improved, thereby enhancing the service life and safety of the composites. The results show that this method greatly improves the chemical activity, hydrophilicity, and surface roughness of UHMWPE fibers with minimal damage, rendering it a promising choice for industrial applications. [Display omitted] • A new strategy for UHMWPE fiber modification applicable to rubber matrix was provided. • A rubber material that can be quickly vulcanized at low temperatures for use in textile core conveyor belts was prepared. • The H pull-out force between the modified UHMWPE fiber and rubber reached 165 N, which reached the application level. • The interfacial bonding mechanism and chemical reaction processes between modified fibers and rubber are elucidated. [ABSTRACT FROM AUTHOR]

A facile and efficient mussel-like inspired modification method was developed to improve the interfacial adhesion of aramid fibers/rubber composites. The surfaces of aramid fibers were pre-deposited by poly(catechol/polyamine) (PCPA) layer, which was formed via the oxidation polymerization of catechol/polyamine (CPA) under UV irradiation. Then, the PCPA-coated fibers were further grafted with ethylene glycol diglycidyl ether (EGDE) to introduce epoxy groups onto aramid fibers surface. The kinetics of catechol oxidation was investigated by UV–vis measurements, suggesting that UV irradiation accelerated the polymerization process of CPA. The effects of EGDE concentration and grafting time on the adhesion force between aramid fibers and rubber matrix were evaluated by pull-out test, and a maximum increase of 85.6% in adhesion force was achieved, even better than that by dopamine in our previous study (a 67.5% improvement). Compared with the method based on dopamine chemistry, this method has advantages of lower cost (less than 1% of the price of dopamine) and shorter reaction time (3 h less in pre-deposition time). This study provides a new efficient strategy for fibers surface functionalization, which has promising application in rubber industry. [ABSTRACT FROM AUTHOR]

• This article reviews the surface modification methods of aramid fiber and its composite materials. • Interfacial adhesion is important for aramid fiber reinforced composites. • The interfacial stress transfer mechanism of aramid fiber reinforced composites is still unclear. Aramid fiber (AF), which has excellent comprehensive properties such as low density, high specific strength, and high specific modulus, is widely used in composites reinforcement. AF-reinforced composites (AFRPs), which are very suitable for preparing advanced engineering materials, have drawn much attention due to their excellent properties. However, the smooth and chemically inert surface of the AF severely limits its applications. Various methods have been conducted to modify the surface of AF to improve the interfacial adhesion between fiber and matrix. The purpose of surface modification of AF is to improve the surface chemical activity and increase the surface roughness, which aims to achieve an excellent chemical bonding and mechanical interlocking between fiber and matrix. The major focus of this review is the surface and interface modification of AF. In this review, we briefly summarize the recent progress of different surface modification methods of AF and its reinforcement to polymers. Finally, some existing problems of AFRPs as well as future research prospects are discussed. [ABSTRACT FROM AUTHOR]